Safety device



R. H. HILL SAFETY DEVICE Dec. 2, 1952 Filed Jan. 27, 1951 INI'EN'I'OR.

ROBERT H. HILL Patented Dec. 2, 1952 SAFETY DEVICE Rober'tH. Hill,El'gin, 111., assignorto The Marison. Company, Elgin llt, a corporationof. Illinois Application January 2'7, 1951, Serial No. $38,179

5 Claims. (01. 220-80) This invention relates to a safety device andmore particularly to a device adapted for use with a metallic cylinderof the kind, in which a fluid under pressure may be transported andstored.

The safety device which has been used heretoforewith a cylinder of theaforesaid character has either been afforded by a frangible disc or by afusible plug, theuse of the latter-being for the most part confined tocylinders in which a permanent gas such as oxygen is transported andstored. Each of these types of safety devices has inherent objectionsand neither has proven to be entirely satisfactory.

Thus, the frangible discs that have been em-- ployed heretofore usuallyhave been machined to very clcse limits which, of course, is relativelyexpensive, but the principal objection to discs of this character hasbeen that they are: subject to fatigueand eventual breakage, especiallyin those circumstances where a cylinder with which such adisc is usedmay from time to time be subjected to heat as for example by being.exposed to the sun during the day so that the cylinder may cool duringthe night. Such alternate heating and cooling (which may be effected in"other Ways) "resultsin a building up and a reduction of pressure in thecylinder, and, while the pressure may not reach that degree of pressurefor which the discis set to release, it nevertheless subjects the discto such pressure that fatigue and eventual breakage of the disc results.

Fusible plugs of the aforesaid character of course afford protectiononly in instances where the cylinder with which such a plug is used issubjected to heat since such a plug has been arranged to give way whenthe portion of the cylinder in which the plug is mounted has beensubject to at least a predetermined temperature. This, therefore, doesnot afford protection in an instance Where excessive pressure is builtup in the cylinder under circumstances such that the cylinder is notsubjected to such a temperature as would cause the fusible plug to giveway.

Experience has also shown that it is quite difficult to arrange eitherof the aforesaidtypes of safety devices in such a Way that the degree ofpressure or temperature under which such a device is to let go may beaccurately controlled and it has been observed that when a plurality ofcylinders each including a safety disc of the frangible type, or asafety plug of the fusible type, have been subjected to identicalcircumstances of such a nature that release of the devices shouldbeeffected, the safety devices associated with the respective cylinders;usually donot'release simpl taneously but rather that the devicesrelease one at a time over a relatively prolonged period; It is,ofcourse, desirable that a safety device employed with thecylinder ofthe aforesaid character be of such nature that it will release underpredetermined accurately ascertained circurn stances.

It is known that the moment of resistance or bending moment(hereinafterreferred to as, bending moment) of a column or strut(hereinafter referred to as a strut) maybe quite accurately determinedand the primary object of this invention is to afforda safety deviceforuse with a cylinder of the aforesaid character and wherein thebendingmoment of astrut is the determinative factor for thereleased the safetydevice.

Other objects of the invention are to utilize, as a strut, a relativelyshort rod to maintain closed a pressure reliefvalve; to so mount such arod that one of the supports therefor will be subjected to pressurewithin a fluid containing cylinder on which my novel safetydevice ismounted; to employ frangible sealing means in association with the strutembodying portions of my novel safety device so as to insure againstseepage or other undesirable loss of fluid from within the tank; to so,arrange the elements or my novel safety device that in the eventofarelease thereof, the device may be quickly arranged for reuse byinserting a new strut therein; and to provide a safety device oftheaforesaid cha acter that will be efiicient and accurate "use and whichwill be of simple and eeoho-m-icalconstruction.

Other and further'obj ects of the present inven tion will be apparentfrom the following desc-r-ip tion and claims and "are illustrated in theaccompanying drawing which. by way of illustration, shows a preferredembodiment of the present vention andthe principles thereof and what Inow consider to be the best mode in which have contemplated applyingthese principles. Otherembod-iments of the invention embodying the "sameor equivalent principles may be used and structural changesmay be madeas desired by those skilled inthe artwithout departing from the presentinvention and the purview cf the appended claims.

Fig. 1 is a view, partly inelevatic andpart'ly in section, showing aportion of a f containing cylinder and the usual outlet fixtureassociated therewith and on which outlet fixture my novel safetydeviceis mounted; l

Fig. 2 is a longitudinal sectional view-of "my safety device asillustrated in Fig. 1, Fig. 2 being drawn to a larger scale than Fig. 1and showing my safety device in the unreleased position thereof Fig. 3is a fragmentary view similar to Fig. 2 showing my safety device in thereleased position thereof; and

Figs. 4, 5 and 6 are transverse sectional detail views takensubstantially and respectively on the line 4-4, 5-5 and 66 of Fig. 2.

In the accompanying drawing I have shown a fragment of a fluidcontaining cylinder C of a conventional construction and having theconventional fitting F mounted in the outlet opening thereof. Thefitting F includes a discharge passage H] which leads to the usualoutlet ll, discharge through the outlet ll being controlled by a valveincluding the stem l2. An outlet passage [3 leads from the dischargepassage I through a threaded boss I4 provided on the fitting F inwardlyof the outlet ll. My novel safety device is adapted to be mounted onthis threaded boss.

My safety device includes a body l5 having a tapped opening l6 extendinginwardly from the larger end thereof and terminating in a shoulder IT.The tapped opening [6 is adapted to be securely fitted onto the threadedboss M, as best shown in Figs. 2 and 3, and a gasket la is interposedbetween an imperforate disc is, engaged with the shoulder l1, and theinner end of the boss I4 when the body I5 is properly mounted on thethreaded boss l4, this gasket and disc affording a fluid tight seal toprevent undesirable escape of fluid from cylinder C through the passagesI0 and I3. The disc I9 is frangible and may be made of a wide variety ofmaterials. For example, the disc may be of lead or other frangible metalor may be made of a plastic material or even of paper of suitablethickness. The gasket is may also be lead or other suitable and somewhatyieldable material.

Rupture or shear of the disc [9 is prevented by the apparatus mounted inthe head portion of the body [5. Thus a bore 2|, that communicates withpassage l3, leads inwardly from the shoulder l1 and a recess 22 ofreduced diameter is provided at the inner end of the bore whereby theshoulder 23 is afforded at the inner end of the bore. A piston 24 ismounted in the bore 2| to be reciprocal therein and normally, as shownin Fig. 2, the inner end of the piston 24 rests against the adjacentsurface of the disc l9 to thereby reinforce the same and prevent rupturethereof so long as the pressure in the cylinder C does not exceed apredetermined degree. In order to maintain the piston in engagement withthe disc IS a strut member 25 is provided which, in the presentinstance, is cylindrical in form and which has one end thereof mountedin a socket 26 in the inner face of the piston 24 while the otherthereof is mounted in a socket 21 provided at the bottom of the recess22. When the piston is disposed in engagement withthe disc l9 it closesoff flow through the discharge passages 28 which lead from the bore 2|to the exterior of the body [5.

It is the strut 25 that is effective to maintain the piston 24 inengagement with the disc l9 and thereby prevent rupture or shear of thedisc until a predetermined pressure has been built up in the cylinder C.When, however, the pressure in the cylinder attains a predetermineddegree, then the force exerted through the disc 19 onto the piston 24will be sufiicient to cause buckling or bending of the strut 25 and whenthe strut 25 so bends, the piston 24 moves away from the disc I9 whichtherefore shears and the piston is driven into engagement with theshoulder 23. This discloses the discharge passages 28 and thereuponfluid flowing from the cylinder 0 through the discharge passage [0 andoutlet passage [3 enables pressure within the cylinder C to be relieved.Thus it will be seen that it is the bending moment of the strut 25 thatcontrols the release of my novel safety device.

In the present instance the strut C is of cylindrical configuration anddesirably the length of the strut is from four to ten times the diameterthereof. The strut as such is made from a metal such as copper or silverthat is substantially free of impurities. In the present instance thestrut 25 is formed of copper and is substantially .080 inch in diameterand substantially .625 inch in length. The diameter of the piston 24 is.3125 inch. Under such circumstances the bending moment of the strut 25is such that release of my safety device will be effected when apressure of 1800 pounds per square inch is attained in the cylinder C.

Once my safety device has released and the parts have assumedsubstantially the position shown in Fig. 3, my safety device may beremoved from the threaded boss I4 and thereupon the bent strut 25 may beremoved by first removing the piston 24. Thereafter a new strut 25 isarranged in the position of the strut 25 shown in the drawings and thebody I5 is again fitted upon the threaded boss [4 with a gasket 58 andthe disc 19 in the positions shown in Fig. .2 and, when the parts areproperly positioned, the adjacent end of the piston 24 will be incontact with the disc I9.

It will be manifest from the foregoing description that I have provideda safety device which enables the hereinabove set forth and kindredobjects of this invention to be realized and while I have illustratedand described a preferred embodiment of my invention, it is to beunderstood that this is capable of variation and modification, and Itherefore do not wish to be limited to the precise details set forth,but desire to avail myself of such changes and alterations as fallwithin the purview of the following claims.

I claim:

1. A safety device of the kind described including a body having apiston reciprocally mounted therein and on one face of which thepressure of a confined fluid is adapted to be impressed, a collapsiblestrut in said body and engaged at right angles with the other face ofsaid piston for preventing movement of the piston until at least apredetermined fluid pressure is impressed on said piston wherebycollapse of said strut is eifected, and discharge means including anoutlet port in said body disclosed upon movement of said piston afterthe collapse of said strut and through which discharge means the fluidmay be released after the predetermined fluid pressure is impressed onsaid. piston.

2. A safety device of the kind described including a body having abottomed bore therein which opens through one end thereof, a piston of adiameter corresponding to said bore mounted in said bore for movementtherein and upon which the pressure of a confined fluid may beimpressed, a collapsible one-piece strut disposed axially of the borebetween the bottom of said bore and said piston for preventing movementof said piston until at least a predetermined fluid pressure isimpressed on said piston whereby collapse of said strut is effected, anddischarge means including an outlet port in said body disclosed uponmovement of said piston after the collapse of said strut and throughwhich discharge means the fluid may be released.

3. A safety device of the kind described including a body having atapped opening extending thereinto from one end thereof and adapted tobe mounted on a threaded boss having a passage therein adapted tocommunicate with a confined fluid, said body also having a bottomed boreextended thereinto from the inner end of said tapped opening, a pistonmounted in said bore and upon which pressure of confined fluidcommunicated through said passage may be impressed, a collapsibleone-piece strut in said body arranged axially of the bore between thebottom of the bore and the inner face of said piston for preventingmovement of the piston until at least a predetermined fluid pressure isimpressed thereon whereby collapse of said strut is effected, dischargemeans including an outlet port in said body disclosed upon movement ofsaid piston after the collapse of said strut and through which dischargemeans the fluid may be released, the piston having a diametercorresponding to the diameter of said bore so as to be slidably engagedwith the inner side walls of said bore.

4. A safety device of the kind described including a body having anopening extended thereinto from one end thereof, said body also having abore extended thereinto from the inner end of said opening, said borebeing smaller than said opening whereby a shoulder is afforded at theinner end of the opening and on which an imperforate frangible disc maybe disposed to seal off said bore from said opening, a piston in saidbore behind the disc and engageable with the disc to reinforce the sameand on which the pressure of a confined fluid effective on said disc maybe impressed, and a strut in said bore extending axially of and betweenthe closed end of the bore and the inner face of said piston forpreventing movement of the piston until at least a predetermined fluidpressure is impressed on said piston whereby collapse of said strut iseffected, said body having a discharge port there-in communicating withsaid bore and adapted to be disclosed upon movement of said piston afterthe collapse of said strut and through which the confined fluid mayescape following a rupture of said disc upon retraction of said pistonfrom engagement with said disc after collapse of said strut, the pistonhaving a diameter corresponding to the diameter of said bore so as to beslidably engaged with the inner side walls of said bore.

5. A safety device of the kind described including a body having atapped opening extending thereinto from one end thereof, said body alsohaving a bore extended thereinto from the inner end of said opening,said bore having one end closed and being smaller than said openingwhereby a shoulder is afforded at the inner end of the opening, athreaded boss having a passage therein adapted to communicate with aconfined fluid, said boss being extended into said tapped opening, animperforate frangible disc disposed between said shoulder and the innerend of said bore when said body is securely mounted on said boss, saiddisc being eifective to seal off said bore from said passage, a pistonin said bore having an outer face engageable with the disc to reinforcethe same and on which outer face fluid pressure effective on said discmay be impressed, and a strut positioned axially in said bore andaxially of said piston, one end of said strut being engaged with theinner face of the piston for preventing movement thereof until at leasta predetermined fluid pressure is impressed on the piston wherebycollapse of the strut is effected, said body having a discharge porttherein communicating with said bore and disposed to be disclosed uponmovement of said piston after collapse of the strut and through whichthe confined fluid may escape following a rupture of the disc uponretraction of said piston from engagement with the disc after collapseof the strut, the said strut being disposed centrally in said bore bymeans of sockets at the closed end of the bore and the inner face of thepiston, respectively, in which sockets the ends of the strut areinserted, and the piston having a diameter corresponding to the diameterof said bore so as to be slidably engaged with the inner side walls ofsaid bore.

ROBERT H. HILL.

REFERENCES CITED The following references are of record. in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 2,079,164 Glab May 4, 19372,263,840 Franck Nov. 25, 1941 2,353,254 McCandless July 11, 1944

